1. Technical Field
The present disclosure generally relates to ablation systems. More particularly, the present disclosure is directed to ablation systems, probes, and methods for reducing or eliminating energy radiating from an ablation probe into a surgical environment.
2. Background of Related Art
In the treatment of diseases such as cancer, certain types of cancer cells have been found to denature at elevated temperatures (which are slightly lower than temperatures normally injurious to healthy cells.) These types of treatments, known generally as hyperthermia therapy, typically utilize electromagnetic radiation to heat diseased cells to temperatures above 41° C., while maintaining adjacent healthy cells at lower temperatures where irreversible cell destruction will not occur. Other procedures using electromagnetic radiation to heat tissue include ablation and coagulation. These procedures are typically done to denature or kill the targeted tissue.
Many medical procedures and devices that use electromagnetic radiation are known in the art. Some of these procedures and devices are used to treat tissue and organs, such as the prostate, heart, liver, lung, kidney, and breast. These medical procedures and devices can be broken down into two general categories: non-invasive and invasive.
Some non-invasive procedures involve treating tissue (e.g., a tumor) underlying the skin with microwave energy. The microwave energy non-invasively penetrates the skin to reach the underlying tissue. However, this non-invasive procedure may result in unwanted heating of healthy tissue. Thus, non-invasive procedures that use microwave energy require precise temperature control.
Some invasive procedures have been developed in which a microwave antenna probe is either inserted directly into a point of treatment via a normal body orifice or inserted percutaneously. These invasive procedures can provide better temperature control of the tissue being treated. Because of the small difference between the temperature required for denaturing malignant cells and the temperature injurious to healthy cells, a known heating pattern and predictable temperature control is important so that heating is confined to the tissue being treated. For instance, hyperthermia treatment at the threshold temperature of about 41.5° C. generally has little effect on most malignant growth of cells. However, at slightly elevated temperatures above the approximate range of 43° C. to 45° C., thermal damage to most types of normal cells is routinely observed. Accordingly, great care must be taken not to exceed these temperatures in healthy tissue.
To prevent damage to healthy tissue, the non-radiating portion of the ablation probe is cooled with a cooling solution having dielectric properties that are matched to the dielectric properties of the target tissue. When the ablation probe is removed from tissue, however, the probe still has the ability to efficiently radiate microwave energy because of the dielectric buffering provided by the cooling solution. Therefore, if the generator is still powering the probe after it is removed from tissue, individuals near the probe may be unnecessarily exposed to microwave energy.